Liquid crystal composition and liquid crystal display device

ABSTRACT

The invention is to provide a liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of a nematic phase, a small viscosity, a suitable optical anisotropy, a large negative dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or that is suitably balanced between at least two of the characteristics; and is to provide a AM device that has a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth, wherein the liquid crystal composition includes a specific compound having a large negative dielectric anisotropy and a low minimum temperature as a first component and a specific compound having a large negative dielectric anisotropy, and the liquid crystal display device contains this composition.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 of international application of PCTapplication serial no. PCT/JP2009/068104, filed on Oct. 21, 2009, whichclaims the priority benefit of Japan application no. 2008-314827, filedon Dec. 10, 2008. The entirety of each of the above-mentioned patentapplications is hereby incorporated by reference herein and made a partof this specification.

TECHNICAL FIELD

The invention relates mainly to a liquid crystal composition suitablefor use in an active matrix (AM) device and so forth, and an AM deviceand so forth that contain the composition. More specifically, theinvention relates to a liquid crystal composition having negativedielectric anisotropy, and a device containing the composition andhaving a mode such as in-plane switching (IPS), vertical alignment (VA)or polymer sustained alignment (PSA).

TECHNICAL BACKGROUND

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes modes of phase change (PC),twisted nematic (TN), super twisted nematic (STN), electricallycontrolled birefringence (ECB), optically compensated bend (OCB),in-plane switching (IPS), vertical alignment (VA) and polymer sustainedalignment (PSA). A classification based on a driving mode in the deviceincludes a passive matrix (PM) and an active matrix (AM). The PM isfurther classified into static, multiplex and so forth, and the AM isclassified into a thin film transistor (TFT), a metal-insulator-metal(MIM) and so forth. The TFT is further classified into amorphous siliconand polycrystal silicon. The latter is classified into a hightemperature type and a low temperature type according to the productionprocess. A classification based on a light source includes a reflectiontype utilizing natural light, a transmission type utilizing a backlightand a semi-transmission type utilizing both natural light and abacklight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to give anAM device having good general characteristics. Table 1 below summarizesthe relationship between the general characteristics of the two. Thegeneral characteristics of the composition will be further explained onthe basis of a commercially available AM device. The temperature rangeof a nematic phase relates to the temperature range in which the devicecan be used. A desirable maximum temperature of the nematic phase is 70°C. or higher and a desirable minimum temperature of the nematic phase is−10° C. or lower. The viscosity of the composition relates to theresponse time of the device. A short response time is desirable fordisplaying moving images on the device. Accordingly, a small viscosityof the composition is desirable. A small viscosity at a low temperatureis more desirable.

TABLE 1 General Characteristics of Composition and AM Device GeneralCharacteristics General Characteristics No. of Composition of AM Device1 wide temperature range wide usable temperature of a nematic phaserange 2 small viscosity ¹⁾ short response time 3 suitable opticalanisotropy large contrast ratio 4 large positive or negative lowthreshold voltage and small dielectric anisotropy electric powerconsumption large contrast ratio 5 large specific resistance largevoltage holding ratio and large contrast ratio 6 high stability toultraviolet long service life light and heat ¹⁾ A liquid crystalcomposition can be injected into a liquid crystal cell in a shorterperiod of time.

The optical anisotropy of the composition relates to the contrast ratioof the device. The product (Δn×d) of the optical anisotropy (Δn) of thecomposition and the cell gap (d) of the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends onthe kind of operating mode. In a device having a VA mode, a suitablevalue is in the range of 0.30 μm to 0.40 μm, and in a device having anIPS mode, a suitable value is in the range of 0.20 μm to 0.30 μm. Inthis case, a composition having a large optical anisotropy is desirablefor a device having a small cell gap. A large absolute value of thedielectric anisotropy in the composition contributes to a low thresholdvoltage, small electric power consumption and a high contrast ratio ofthe device. Accordingly, a large absolute value of the dielectricanisotropy is desirable. A large specific resistance of the compositioncontributes to a large voltage holding ratio and a large contrast ratioof the device. Accordingly, a composition having a large specificresistance is desirable at room temperature and also at a hightemperature in the initial stage. A composition having a large specificresistance is desirable at room temperature and also at a hightemperature after it has been used for a long time. The stability of thecomposition to ultraviolet light and heat relates to the service life ofthe liquid crystal display device. In the case where the stability ishigh, the device has a long service life. Such characteristics aredesirable for an AM device used in a liquid crystal projector, a liquidcrystal television and so forth.

A composition having positive dielectric anisotropy is used for an AMdevice having a TN mode. On the other hand, a composition havingnegative dielectric anisotropy is used for an AM device having a VAmode. A composition having positive or negative dielectric anisotropy isused for an AM device having an IPS mode. A composition having positiveor negative dielectric anisotropy is used for an AM device having a PSAmode. Examples of the liquid crystal composition having negativedielectric anisotropy are disclosed in the following patent documentsNo. 1 to No. 3.

PRIOR ART Patent Document

Patent document No. 1: WO 2006-93189 A.

Patent document No. 2: WO 2006-98289 A.

Patent document No. 3: WO 2007-83561 A.

A desirable AM device has characteristics such as a wide temperaturerange in which the device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. Response time that is even one millisecondshorter than that of the other devices is desirable. Thus, desirablecharacteristics of the composition include a high maximum temperature ofa nematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a suitable optical anisotropy, a large positive or negativedielectric anisotropy, a large specific resistance, a high stability toultraviolet light and a high stability to heat.

OUTLINE OF THE INVENTION Subject to be Solved by the Invention

One of the aims of the invention is to provide a liquid crystalcomposition that satisfies at least one of characteristics such as ahigh maximum temperature of a nematic phase, a low minimum temperatureof a nematic phase, a small viscosity, a suitable optical anisotropy, alarge negative dielectric anisotropy, a large specific resistance, ahigh stability to ultraviolet light and a high stability to heat.Another aim is to provide a liquid crystal composition that is suitablybalanced between at least two of the characteristics. A further aim isto provide a liquid crystal display device that contains such acomposition. An additional aim is to provide a composition that has asuitable optical anisotropy which means a large optical anisotropy or asmall optical anisotropy, a large negative dielectric anisotropy, a highstability to ultraviolet light and so forth, and is to provide an AMdevice that has a short response time, a large voltage holding ratio, alarge contrast ratio, a long service life and so forth.

Means for solving the Subject

The invention concerns a liquid crystal composition that has negativedielectric anisotropy and includes at least one compound selected fromthe group of compounds represented by formula (1) as a first componentand at least one compound selected from the group of compoundsrepresented by formula (2) as a second component, and concerns a liquidcrystal display device containing this composition:

wherein R¹ is alkenyl having 2 to 12 carbons; R² and R³ areindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; the ring Ais independently 1,4-cyclohexylene or 1,4-phenylene; Z¹ is independentlya single bond, ethylene, methyleneoxy or carbonyloxy; one of X¹ and X²is fluorine and the other is chlorine; and m and k are independently 1,2 or 3.

Effect of the Invention

An advantage of the invention is a liquid crystal composition thatsatisfies at least one of characteristics such as a high maximumtemperature of a nematic phase, a low minimum temperature of a nematicphase, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. One aspectof the invention is a liquid crystal composition that is suitablybalanced between at least two of the characteristics. Another aspect isa liquid crystal display device that contains such a composition. Afurther aspect is a composition that has a suitable optical anisotropy,a large negative dielectric anisotropy, a high stability to ultravioletlight and so forth, and an AM device that has a short response time, alarge voltage holding ratio, a large contrast ratio, a long service lifeand so forth.

EMBODIMENT TO CARRY OUT THE INVENTION

Usage of the terms in this specification is as follows. The liquidcrystal composition of the invention and the liquid crystal displaydevice of the invention may be abbreviated to “the composition” and “thedevice,” respectively. “A liquid crystal display device” is a genericterm for a liquid crystal display panel and a liquid crystal displaymodule. “A liquid crystal compound” is a generic term for a compoundhaving a liquid crystal phase such as a nematic phase or a smecticphase, and also for a compound having no liquid crystal phases but beinguseful as a component of a composition. Such a useful compound has asix-membered ring such as 1,4-cyclohexylene and 1,4-phenylene, and arod-like molecular structure. An optically active compound and apolymerizable compound may occasionally be added to the composition.Even in the case where these compounds are liquid crystalline, thecompounds are classified as an additive herein. At least one compoundselected from the group of compounds represented by formula (1) may beabbreviated to “the compound (1).” “The compound (1)” means onecompound, or two or more compounds represented by formula (1). The samerules apply to compounds represented by the other formulas. “Arbitrary”is used not only in cases where the position is arbitrary but also incases where the number is arbitrary. However, it is not used in caseswhere the number is 0 (zero).

A higher limit of the temperature range of a nematic phase may beabbreviated to “the maximum temperature.” A lower limit of thetemperature range of a nematic phase may be abbreviated to “the minimumtemperature.” That “specific resistance is large” means that acomposition has a large specific resistance at room temperature and alsoat a temperature close to the maximum temperature of a nematic phase inthe initial stage, and that the composition has a large specificresistance at room temperature and also at a temperature close to themaximum temperature of a nematic phase even after it has been used for along time. That “a voltage holding ratio is large” means that a devicehas a large voltage holding ratio at room temperature and also at a hightemperature in the initial stage, and that the device has a largevoltage holding ratio at room temperature and also at a temperatureclose to the maximum temperature of a nematic phase even after it hasbeen used for a long time. When characteristics such as opticalanisotropy are explained, values obtained according to the measuringmethods that are described in Examples will be used. A first componentmeans one compound, or two or more compounds. “The ratio of the firstcomponent” is expressed as a percentage by weight (% by weight) of thefirst component based on the total weight of the liquid crystalcomposition. The same rule applies to the ratio of a second componentand so forth. The ratio of an additive mixed with the composition isexpressed as a percentage by weight (% by weight) or weight parts permillion (ppm) based on the total weight of the liquid crystalcomposition.

The symbol R¹ is used for a plurality of compounds in the chemicalformulas of component compounds. The meanings of R¹ may be the same ordifferent in two arbitrary compounds among these. In one case, forexample, R¹ of the compound (1-1) is ethyl and R¹ of the compound (1-2)is ethyl. In another case, R¹ of the compound (1-1) is ethyl and R¹ ofthe compound (1-2) is propyl. The same rule applies to the symbols R²,Z¹ and so forth.

The invention includes the following items.

-   Item 1. A liquid crystal composition having negative dielectric    anisotropy and including at least one compound selected from the    group of compounds represented by formula (1) as a first component    and at least one compound selected from the group of compounds    represented by formula (2) as a second component:

wherein R¹ is alkenyl having 2 to 12 carbons; R² and R³ areindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; the ring Ais independently 1,4-cyclohexylene or 1,4-phenylene; Z¹ is independentlya single bond, ethylene, methyleneoxy or carbonyloxy; one of X¹ and X²is fluorine and the other is chlorine; and m and k are independently 1,2 or 3.

-   Item 2. The liquid crystal composition according to item 1, wherein    the first component is at least one compound selected from the group    of compounds represented by formula (1-1) to formula (1-7):

wherein R¹ is alkenyl having 2 to 12 carbons; and R² is alkyl having 1to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogenis replaced by fluorine.

-   Item 3. The liquid crystal composition according to item 2, wherein    the first component is at least one compound selected from the group    of compounds represented by formula (1-1).-   Item 4. The liquid crystal composition according to item 2, wherein    the first component is at least one compound selected from the group    of compounds represented by formula (1-4).-   Item 5. The liquid crystal composition according to item 2, wherein    the first component is a mixture of at least one compound selected    from the group of compounds represented by formula (1-1) and at    least one compound selected from the group of compounds represented    by formula (1-4).-   Item 6. The liquid crystal composition according to any one of items    1 to 5, wherein the second component is at least one compound    selected from the group of compounds represented by formula (2-1) to    formula (2-3):

wherein R² and R³ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

-   Item 7. The liquid crystal composition according to item 6, wherein    the second component is at least one compound selected from the    group of compounds represented by formula (2-2).-   Item 8. The liquid crystal composition according to any one of items    1 to 7, wherein the ratio of the first component is in the range of    5% by weight to 70% by weight and the ratio of the second component    is in the range of 5% by weight to 30% by weight, based on the total    weight of the liquid crystal composition.-   Item 9. The liquid crystal composition according to any one of items    1 to 8, further including at least one compound selected from the    group of compounds represented by formula (3) as a third component:

wherein R⁴ and R⁵ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; the ring B and the ring C are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene; Z² is independently a single bond, ethyleneor carbonyloxy; and j is 1, 2 or 3.

-   Item 10. The liquid crystal composition according to item 9, wherein    the third component is at least one compound selected from the group    of compounds represented by formula (3-1) to formula (3-12):

wherein R⁴ and R⁵ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

-   Item 11. The liquid crystal composition according to item 10,    wherein the third component is at least one compound selected from    the group of compounds represented by formula (3-1).-   Item 12. The liquid crystal composition according to item 10,    wherein the third component is a mixture of at least one compound    selected from the group of compounds represented by formula (3-1)    and at least one compound selected from the group of compounds    represented by formula (3-5).-   Item 13. The liquid crystal composition according to item 10,    wherein the third component is a mixture of at least one compound    selected from the group of compounds represented by formula (3-1)    and at least one compound selected from the group of compounds    represented by formula (3-7).-   Item 14. The liquid crystal composition according to item 10,    wherein the third component is a mixture of at least one compound    selected from the group of compounds represented by formula (3-1),    at least one compound selected from the group of compounds    represented by formula (3-5) and at least one compound selected from    the group of compounds represented by formula (3-7).-   Item 15. The liquid crystal composition according to any one of    items 9 to 14, wherein the ratio of the third component is in the    range of 20% by weight to 70% by weight based on the total weight of    the liquid crystal composition.-   Item 16. The liquid crystal composition according to any one of    items 1 to 15, further including at least one compound selected from    the group of compounds represented by formula (4) as a fourth    component:

wherein R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁶ is alkylhaving 1 to 12 carbons; the ring D is independently 1,4-cyclohexylene or1,4-phenylene; Z¹ is independently a single bond, ethylene, methyleneoxyor carbonyloxy; and p is 1, 2 or 3.

-   Item 17. The liquid crystal composition according to item 16,    wherein the fourth component is at least one compound selected from    the group of compounds represented by formula (4-1) to formula    (4-7):

wherein R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; and R⁶ isalkyl having 1 to 12 carbons.

-   Item 18. The liquid crystal composition according to item 17,    wherein the fourth component is at least one compound selected from    the group of compounds represented by formula (4-1).-   Item 19. The liquid crystal composition according to item 17,    wherein the fourth component is at least one compound selected from    the group of compounds represented by formula (4-7).-   Item 20. The liquid crystal composition according to item 17,    wherein the fourth component is a mixture of at least one compound    selected from the group of compounds represented by formula (4-1)    and at least one compound selected from the group of compounds    represented by formula (4-7).-   Item 21. The liquid crystal composition according to item 17,    wherein the fourth component is a mixture of at least one compound    selected from the group of compounds represented by formula (4-4)    and at least one compound selected from the group of compounds    represented by formula (4-7).-   Item 22. The liquid crystal composition according to any one of    items 16 to 21, wherein the ratio of the fourth component is in the    range of 5% by weight to 50% by weight based on the total weight of    the liquid crystal composition.-   Item 23. A liquid crystal composition having negative dielectric    anisotropy and consisting essentially of at least one compound    selected from the group of compounds represented by formula (1) as a    first component, at least one compound selected from the group of    compounds represented by formula (2) as a second component, and at    least one compound selected from the group of compounds represented    by formula (3) as a third component:

wherein R¹ is alkenyl having 2 to 12 carbons; R², R³, R⁴ and R⁵ areindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; the ring Ais independently 1,4-cyclohexylene or 1,4-phenylene; the ring B and thering C are independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene, 3-fluoro-1,4-phenylene or2,5-difluoro-1,4-phenylene; Z¹ is independently a single bond, ethylene,methyleneoxy or carbonyloxy; Z² is independently a single bond, ethyleneor carbonyloxy; one of X¹ and X² is fluorine and the other is chlorine;and m, k and j are independently 1, 2 or 3.

-   Item 24. The liquid crystal composition according to claim 23,    wherein the ratio of the first component is in the range of 5% by    weight to 50% by weight, the ratio of the second component is in the    range of 10% by weight to 50% by weight, and the ratio of the third    component is in the range of 20% by weight to 70% by weight, based    on the total weight of the liquid crystal composition.-   Item 25. A liquid crystal composition having negative dielectric    anisotropy and consisting essentially of at least one compound    selected from the group of compounds represented by formula (1) as a    first component, at least one compound selected from the group of    compounds represented by formula (2) as a second component, at least    one compound selected from the group of compounds represented by    formula (3) as a third component, and at least one compound selected    from the group of compounds represented by formula (4):

wherein R¹ is alkenyl having 2 to 12 carbons; R², R³, R⁴ and R⁵ areindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁶ is alkylhaving 1 to 12 carbons; the ring A and the ring D are independently1,4-cyclohexylene or 1,4-phenylene; the ring B and the ring C areindependently 1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene; Z¹ isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; Z²is independently a single bond, ethylene or carbonyloxy; one of X¹ andX² is fluorine and the other is chlorine; and m, k, j and p areindependently 1, 2 or 3.

-   Item 26. The liquid crystal composition according to item 25,    wherein the ratio of the first component is in the range of 5% by    weight to 70% by weight, the ratio of the second component is in the    range of 5% by weight to 30% by weight, the ratio of the third    component is in the range of 20% by weight to 70% by weight, and the    ratio of the fourth component is in the range of 5% by weight to 50%    by weight, based on the total weight of the liquid crystal    composition.-   Item 27. The liquid crystal composition according to items 23 to 26,    wherein the first component is at least one compound selected from    the group of compounds represented by formula (1-1) to formula (1-7)    :

wherein R¹ is alkenyl having 2 to 12 carbons; and R² is alkyl having 1to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogenis replaced by fluorine.

-   Item 28. The liquid crystal composition according to any one of    items 23 to 27, wherein the second component is at least one    compound selected from the group of compounds represented by formula    (2-1) to formula (2-3):

wherein R² and R³ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

-   Item 29. The liquid crystal composition according to items 23 to 28,    wherein the third component is at least one compound selected from    the group of compounds represented by formula (3-1) to formula    (3-12):

wherein R⁴ and R⁵ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

-   Item 30. The liquid crystal composition according to claims 25 to    29, wherein the fourth component is at least one compound selected    from the group of compounds represented by formula (4-1) to formula    (4-7):

wherein R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; and R⁶ isalkyl having 1 to 12 carbons.

-   Item 31. The liquid crystal composition according to any one of    items 1 to 30, wherein the maximum temperature of a nematic phase is    70° C. or higher, the optical anisotropy (25° C.) at a wavelength of    589 nanometers is 0.08 or more, and the dielectric anisotropy (25°    C.) at a frequency of 1 kHz is −2 or less.-   Item 32. A liquid crystal display device containing the liquid    crystal composition according to any one of items 1 to 31.-   Item 33. The liquid crystal display device according to claim 32,    wherein an operating mode of the liquid crystal display device is a    VA mode, an IPS mode or a PSA mode, and a driving mode of the liquid    crystal display device is an active matrix mode.

The invention further includes the following items: (1) the compositiondescribed above, further including an optically active compound; (2) thecomposition described above, further including an additive, such as anantioxidant, an ultraviolet light absorber and an antifoaming agent; (3)an AM device containing the composition described above; (4) a devicehaving a mode of TN, ECB, OCB, IPS, VA or PSA and containing thecomposition described above; (5) a transmission-type device containingthe composition described above; (6) use of the composition describedabove, as a composition having a nematic phase; and (7) use of thecomposition prepared by the addition of an optically active compound tothe composition described above, as an optically active composition.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, main characteristics of the componentcompounds and main effects of these compounds on the composition will beexplained. Third, a combination of components in the composition,desirable ratios of the component compounds and the basis thereof willbe explained. Fourth, a desirable embodiment of the component compoundswill be explained. Fifth, specific examples of the component compoundswill be shown. Sixth, additives that may be mixed with the compositionwill be explained. Seventh, methods for synthesizing the componentcompounds will be explained. Last, use of the composition will beexplained.

First, the constitution of component compounds in the composition willbe explained. The compositions of the invention are classified into thecomposition A and the composition B. The composition A may furtherinclude any other liquid crystal compound, an additive and an impurity.“Any other liquid crystal compound” is a liquid crystal compound that isdifferent from the compound (1), the compound (2), the compound (3) andthe compound (4). Such a compound is mixed with the composition for thepurpose of further adjusting characteristics of the composition. Of anyother liquid crystal compound, a smaller amount of a cyano compound isdesirable in view of its stability to heat or ultraviolet light. A moredesirable ratio of the cyano compound is 0% by weight. The additiveincludes an optically active compound, an antioxidant, an ultravioletlight absorber, a coloring matter, an antifoaming agent, a polymerizablecompound and a polymerization initiator. The impurity is compounds andso forth which have contaminated component compounds in a process suchas their synthesis. Even in the case where the compound is liquidcrystalline, it is classified into an impurity herein.

The composition B consists essentially of compounds selected from thegroup of the compound (1), the compound (2), the compound (3) and thecompound (4). The term “essentially” means that the composition mayinclude an additive and an impurity, but does not include any liquidcrystal compound other than these compounds. The composition B has asmaller number of components than the composition A. The composition Bis preferable to the composition A in view of cost reduction. Thecomposition A is preferable to the composition B in view of the factthat physical properties can be further adjusted by adding any otherliquid crystal compound.

Second, main characteristics of the component compounds and main effectsof the compounds on the characteristics of the composition will beexplained. The main characteristics of the component compounds aresummarized in Table 2 on the basis of the effects of the invention. InTable 2, the symbol L stands for “large” or “high”, the symbol M standsfor “medium”, and the symbol S stands for “small” or “low.” The symbolsL, M and S are classified according to a qualitative comparison amongthe component compounds, and 0 (zero) means that “a value is nearlyzero.”

TABLE 2 Characteristics of Compounds Compound Compound Compound CompoundCompounds (1) (2) (3) (4) Maximum S-L S-M S-L S-L Temperature ViscosityM M-L S-M M-L Optical M M S-L M-L Anisotropy Dielectric S-L ¹⁾ M-L ¹⁾ 0S-L ¹⁾ Anisotropy Specific L L L L Resistance ¹⁾ Value of opticalanisotropy is negative, and the symbol expresses the magnitude of theabsolute value.

Main effects of the component compounds on the characteristics of thecomposition upon mixing the component compounds with the composition areas follows. The compound (1) increases the absolute value of thedielectric anisotropy. The compound (2) increases the absolute value ofthe dielectric anisotropy, and decreases the minimum temperature. Thecompound (3) decreases the viscosity, or increases the maximumtemperature. The compound (4) decreases the minimum temperature.

Third, a combination of the components in the composition, desirableratios of the component compounds and the basis thereof will beexplained. A combination of the components in the composition is thefirst and second components, the first, second and third components, thefirst, second and forth components and the first, second, third andforth components. A combination of the components in the desirablecomposition is the first, second and third components and the first,second, third and fourth components.

A desirable ratio of the first component is 5% by weight or more forincreasing the absolute value of the dielectric anisotropy, and 70% byweight or less for decreasing the minimum temperature. A more desirableratio is in the range of 10% by weight to 65% by weight. An especiallydesirable ratio is in the range of 15% by weight to 60% by weight.

A desirable ratio of the second component is 5% by weight or more forincreasing the absolute value of the dielectric anisotropy, and 30% byweight or less for decreasing the viscosity. A more desirable ratio isin the range of 5% by weight to 25% by weight. An especially desirableratio is in the range of 5% by weight to 20% by weight.

A desirable ratio of the third component is 20% by weight or more fordecreasing the viscosity or for increasing the maximum temperature, and70% by weight or less for increasing the absolute value of thedielectric anisotropy. A more desirable ratio is in the range of 30% byweight to 65% by weight . An especially desirable ratio is in the rangeof 35% by weight to 60% by weight.

A desirable ratio of the fourth component is 5% by weight or more fordecreasing the minimum temperature, and 50% by weight or less fordecreasing the viscosity. A more desirable ratio is in the range of 5%by weight to 45% by weight. An especially desirable ratio is in therange of 10% by weight to 40% by weight.

Fourth, a desirable embodiment of the component compounds will beexplained. R¹ is alkenyl having 2 to 12 carbons. R², R³, R⁴ and R⁵ areindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine. DesirableR² and R³ are each alkyl having 1 to 12 carbons for increasing thestability to ultraviolet light or heat, for instance, or alkoxy having 1to 12 carbons for increasing the absolute value of the dielectricanisotropy. Desirable R⁴ and R⁵ are each alkyl having 1 to 12 carbonsfor increasing the stability to ultraviolet light or heat, for instance,or alkenyl having 2 to 12 carbons for decreasing the minimumtemperature. R⁶ is alkyl having 1 to 12 carbons.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl or heptylfor decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl for decreasing theviscosity. A desirable configuration of —CH═CH— in the alkenyl dependson the position of the double bond. Trans is preferable in the alkenylsuch as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl and3-hexenyl for decreasing the viscosity for instance. Cis is preferablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thealkenyl, straight-chain alkenyl is preferable to branched-chain alkenyl.

Desirable examples of alkenyl in which arbitrary hydrogen is replaced byfluorine are 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More desirable examples are 2,2-difluorovinyland 4,4-difluoro-3-butenyl for decreasing the viscosity.

The ring A is independently 1,4-cyclohexylene or 1,4-phenylene, andarbitrary two of the ring A may be the same or different when m or k is2 or 3. Desirable ring A is each 1,4-cyclohexylene for decreasing theviscosity. The ring B and the ring C are independently1,4-cyclohexylene, 1,4-phenylene, 2-fluoro-1,4-phenylene,3-fluoro-1,4-phenylene or 2,5-difluoro-1,4-phenylene, and two of thering B may be the same or different when j is 2 or 3. Desirable ring Band ring C are each 1,4-cyclohexylene for decreasing the viscosity. Thering D is independently 1,4-cyclohexylene or 1,4-phenylene, andarbitrary two of the ring D may be the same or different when p is 2 or3. Desirable ring D is each 1,4-phenylene for increasing the opticalanisotropy.

Z¹ is independently a single bond, ethylene, methyleneoxy orcarbonyloxy, and arbitrary two of Z¹ may be the same or different whenm, k and p is 2 or 3. Desirable Z¹ is each a single bond for decreasingthe viscosity or methyleneoxy for increasing the absolute value of thedielectric anisotropy. Z² is independently a single bond, ethylene orcarbonyloxy, and two of Z² may be the same or different when j is 2 or3. Desirable Z² is each a single bond for decreasing the viscosity.

One of X¹ and X² is fluorine and the other is chlorine. Desirable X¹ andX² are that X¹ is fluorine and X² is chlorine, for decreasing theminimum temperature.

m, k, j and p are each 1, 2 or 3. Desirable m is 1 for increasing theabsolute value of the dielectric anisotropy. Desirable k and p are each2 for decreasing the minimum temperature. Desirable j is 1 fordecreasing the viscosity.

Fifth, specific examples of the component compounds will be shown. Inthe desirable compounds described below, R⁷ is straight-chain alkylhaving 1 to 12 carbons or straight-chain alkoxy having 1 to 12 carbons.R⁸ and R⁹ are independently straight-chain alkyl having 1 to 12 carbonsor straight-chain alkenyl having 2 to 12 carbons. R¹⁰ is straight-chainalkenyl having 2 to 12 carbons. R¹¹ is straight-chain alkyl having 1 to12 carbons. With regard to the configuration of 1,4-cyclohexylene inthese compounds, trans is preferable to cis for increasing the maximumtemperature.

Desirable compound (1) are the compound (1-1-1) to the compound (1-7-1).More desirable compound (1) are the compound (1-1-1), the compound(1-3-1), the compound (1-4-1), the compound (1-6-1) and the compound(1-7-1). Especially desirable compound (1) are the compound (1-1-1), thecompound (1-4-1) and the compound (1-7-1). Desirable compound (2) arethe compound (2-1-1) to the compound (2-3-1). More desirable compound(2) is the compound (2-2-1). Desirable compound (3) are the compound(3-1-1) to the compound (3-12-1). More desirable compound (3) are thecompound (3-1-1), the compound (3-3-1), the compound (3-5-1), thecompound (3-7-1), the compound (3-8-1), the compound (3-9-1) and thecompound (3-12-1). Especially desirable compound (3) are the compound(3-1-1), the compound (3-5-1), the compound (3-7-1) and the compound(3-12-1). Desirable compound (4) are the compound (4-1-1) and thecompound (4-7-1). More desirable compound (4) are the compound (4-1-1),the compound (4-3-1), the compound (4-4-1), the compound (4-6-1) and thecompound (4-7-1). Especially desirable compound (4) are the compound(4-1-1), the compound (4-4-1) and the compound (4-7-1).

Sixth, additives which may be mixed with the composition will beexplained. Such additives include an optically active compound, anantioxidant, an ultraviolet light absorber, a coloring matter, anantifoaming agent, a polymerizable compound and a polymerizationinitiator. The optically active compound is mixed with the compositionfor the purpose of inducing a helical structure and giving a twist anglein liquid crystals. Examples of such compounds include the compound(5-1) to the compound (5-4). A desirable ratio of the optically activecompound is 5% by weight or less, and a more desirable ratio is in therange of 0.01% by weight to 2% by weight.

An antioxidant is mixed with the composition in order to prevent adecrease in specific resistance that is caused by heating under air, orto maintain a large voltage holding ratio at room temperature and alsoat a high temperature after the device has been used for a long time.

Desirable examples of the antioxidant include the compound (6) where nis an integer from 1 to 9. In the compound (6), desirable n is 1, 3, 5,7 or 9. More desirable n is 1 or 7. The compound (6) where n is 1 iseffective in preventing a decrease in specific resistance that is causedby heating under air, because it has a large volatility. The compound(6) where n is 7 is effective in maintaining a large voltage holdingratio at room temperature and also at a high temperature even after thedevice has been used for a long time, because it has a small volatility.A desirable ratio of the antioxidant is 50 ppm or more for achieving itseffect and is 600 ppm or less for avoiding a decrease in the maximumtemperature or avoiding an increase in the minimum temperature. A moredesirable ratio is in the range of 100 ppm to 300 ppm.

Desirable examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also desirable. A desirable ratio of the ultraviolet light absorberor the light stabilizer is 50 ppm or more for achieving its effect andis 10,000 ppm or less for avoiding a decrease in the maximum temperatureor avoiding an increase in the minimum temperature. A more desirableratio is in the range of 100 ppm to 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition for adjusting to a device having a guest host (GH) mode.A desirable ratio of the coloring matter is in the range of 0.01% byweight to 10% by weight. An antifoaming agent such as dimethyl siliconeoil or methyl phenyl silicone oil is mixed with the composition forpreventing foam formation. A desirable ratio of the antifoaming agent is1 ppm or more for achieving its effect and is 1,000 ppm or less foravoiding a poor display. A more desirable ratio is in the range of 1 ppmto 500 ppm.

A polymerizable compound is mixed with the composition for adjusting toa device having a polymer sustained alignment (PSA) mode. Desirableexamples of the polymerizable compound include compounds having apolymerizable group, such as acrylates, methacrylates, vinyl compounds,vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes,oxetanes) and vinyl ketones. Especially desirable examples of thepolymerizable compound are acrylate derivatives or methacrylatederivatives. A desirable ratio of the polymerizable compound is 0.05% byweight or more for achieving its effect and is 10% by weight or less foravoiding a poor display. A more desirable ratio is in the range of 0.1%by weight to 2% by weight. The polymerizable compound is polymerized onirradiation with ultraviolet light or the like, preferably in thepresence of a suitable initiator such as a photopolymerizationinitiator. Suitable conditions for polymerization, suitable types of theinitiator and suitable amounts thereof are known to a person skilled inthe art and are described in the literature. For example, Irgacure 651(registered trademark), Irgacure 184 (registered trademark) or Darocure1173 (registered trademark) (Ciba Japan K.K.), each of which is aphotopolymerization initiator, is suitable for radical polymerization.The polymerizable compound includes the photopolymerization initiatorpreferably in the range of 0.1% by weight to 5% by weight and mostpreferably in the range of 1% by weight to 3% by weight.

Seventh, methods for synthesizing the component compounds will beexplained. These compounds can be prepared by known methods. Thesynthetic methods will be exemplified as follows. The compound (1-4-1)is prepared by the method described in JP 2000-53602 A. The compound(2-2-1) is prepared by the method described in WO 2006-93189 A. Thecompound (3-1-1) and the compound (3-5-1) are prepared by the methoddescribed in JP S59-176221 A (1984). The compound (4-7-1) is prepared bythe method described in JP S57-114532 A (1982). An antioxidant iscommercially available. The compound where n is 1 in formula (6) isavailable from Sigma-Aldrich Corporation. The compound (6) where n is 7or the like is synthesized according to the method described in U.S.Pat. No. 3,660,505.

Compounds whose synthetic methods are not described above can beprepared according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press), NewExperimental Chemistry Course (Shin Jikken Kagaku Kouza, in Japanese;Maruzen Co., Ltd.). The composition is prepared according to knownmethods using the compounds thus obtained. For example, the componentcompounds are mixed and dissolved in each other by heating.

Last, use of the composition will be explained. Most of the compositionshave a minimum temperature of −10° C. or lower, a maximum temperature of70° C. or higher, and an optical anisotropy in the range of 0.07 to0.20. A device containing this composition has a large voltage holdingratio. The composition is suitable for an AM device. The composition issuitable especially for an AM device having a transmission type. Thecomposition having an optical anisotropy in the range of 0.08 to 0.25may be prepared by adjusting ratios of the component compounds or bymixing with any other liquid crystal compound. The composition can beused as a composition having a nematic phase, or as an optically activecomposition by the addition of an optically active compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for the AM device and the PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA or PSA. Itis especially desirable to use the composition for the AM device havingthe IPS or VA mode. These devices may be of a reflection type, atransmission type or a semi-transmission type. It is desirable to usethe composition for a device having the transmission type. It can beused for an amorphous silicon-TFT device or a polycrystal silicon-TFTdevice. The composition is also usable for a nematic curvilinear alignedphase (NCAP) device prepared by microcapsulating the composition, andfor a polymer dispersed (PD) device in which a three-dimensionalnetwork-polymer is formed in the composition.

EXAMPLES

A composition and a compound were a subject for measurement in order toevaluate characteristics of the composition and the compound to beincluded in the composition. When the subject for measurement was acomposition, the composition itself was measured as a sample, and thevalue obtained was described here. When a subject for measurement was acompound, a sample for measurement was prepared by mixing 15% by weightof the compound and 85% by weight of mother liquid crystals. Thecharacteristic values of the compound were calculated from valuesobtained by measurement, according to a method of extrapolation. Thatis: (extrapolated value)=[(measured value of a sample formeasurement)−0.85×(measured value of mother liquid crystals)]/0.15. Whena smectic phase (or crystals) separated out in this ratio at 25° C., theratio of the compound to the mother liquid crystals was changed step bystep in the order of (10% by weight/90% by weight), (5% by weight/95% byweight) and (1% by weight/99% by weight). The values of the maximumtemperature, the optical anisotropy, the viscosity and the dielectricanisotropy with regard to the compound were obtained by thisextrapolation method.

The components of the mother liquid crystals were as follows.

Characteristics were measured according to the following methods. Mostare methods described in the Standards of Electronic IndustriesAssociation of Japan, EIAJ•ED-2521 A, or the modified methods.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. Thetemperature was measured when part of the sample began to change from anematic phase to an isotropic liquid. A higher limit of the temperaturerange of a nematic phase may be abbreviated to “the maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in glass vials and then kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then the liquid crystal phases were observed. For example,when the sample maintained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., Tc was expressed as ≦−20° C. Alower limit of the temperature range of a nematic phase may beabbreviated to “the minimum temperature.”

Viscosity (bulk viscosity; η; measured at 20° C.; mPa·s): Viscosity wasmeasured by use of an E-type viscometer.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out by use of an Abbe refractometer with apolarizing plate mounted on the ocular, using light at a wavelength of589 nanometers. The surface of the main prism was rubbed in onedirection, and then a sample was dropped on the main prism. A refractiveindex (η∥) was measured when the direction of polarized light wasparallel to that of the rubbing. A refractive index (n⊥) was measuredwhen the direction of polarized light was perpendicular to that of therubbing. The value of optical anisotropy was calculated from theequation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δε; measured at 25° C.): The value of dielectricanisotropy was calculated from the equation: Δ∈=∈∥−∈⊥. Dielectricconstants (∈∥ and ∈⊥) were measured as follows.

-   1) Measurement of a dielectric constant (∈∥): A solution of    octadecyltriethoxysilane (0.16 mL) in ethanol (20 mL) was applied to    a thoroughly cleaned glass substrate. The glass substrate was    rotated with a spinner, and then heated at 150° C. for one hour. A    sample was poured into a VA device in which the distance between the    two glass substrates (cell gap) was 4 micrometers, and then the    device was sealed with an adhesive curable on irradiation with    ultraviolet light. Sine waves (0.5 V, 1 kHz) were applied to the    device, and a dielectric constant (∈∥) in the major axis direction    of liquid crystal molecules was measured after 2 seconds.-   2) Measurement of a dielectric constant (∈⊥): A polyimide solution    was applied to a thoroughly cleaned glass substrate. The glass    substrate was burned, and then the resulting alignment film was    subjected to rubbing. A sample was poured into a TN device in which    the distance between the two glass substrates (cell gap) was 9    micrometers and the twist angle was 80 degrees. Sine waves (0.5 V, 1    kHz) were applied to the device, and a dielectric constant (∈⊥) in    the minor axis direction of liquid crystal molecules was measured    after 2 seconds.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. A sample waspoured into a VA device having a normally black mode, in which thedistance between the two glass substrates (cell gap) was 4 micrometersand the rubbing direction was antiparallel, and then the device wassealed with an adhesive curable on irradiation with ultraviolet light.The voltage to be applied to the device (60 Hz, rectangular waves) wasstepwise increased in 0.02 V increments from 0 V up to 20 V. During theincrease, the device was irradiated with light in the perpendiculardirection, and the amount of light passing through the device wasmeasured. A voltage-transmittance curve was prepared, in which themaximum amount of light corresponded to 100% transmittance and theminimum amount of light corresponded to 0% transmittance. The thresholdvoltage was voltage at 10% transmittance.

Voltage Holding Ratio (VHR-1; 25° C.; %): A TN device used formeasurement had a polyimide-alignment film, and the distance between thetwo glass substrates (cell gap) was 5 micrometers. A sample was pouredinto the device, and then the device was sealed with a UV-polymerizableadhesive. A pulse voltage (60 microseconds at 5 V) was applied to the TNdevice and the device was charged. A decreasing voltage was measured for16.7 milliseconds with a high-speed voltmeter, and the area A betweenthe voltage curve and the horizontal axis in a unit cycle was obtained.The area B was an area without the decrease. The voltage holding ratiowas the percentage of the area A to the area B.

Voltage Holding Ratio (VHR-2; at 80° C.; %): A TN device used formeasurement had a polyimide-alignment film, and the distance between thetwo glass substrates (cell gap) was 5 micrometer. A sample was pouredinto the device, and then the device was sealed with a UV-polymerizableadhesive. A pulse voltage (60 microseconds at 5 V) was applied to the TNdevice and the device was charged. A decreasing voltage was measured for16.7 milliseconds with a high-speed voltmeter and the area A between thevoltage curve and the horizontal axis in a unit cycle was obtained. Thearea B was an area without the decrease. The voltage holding ratio was apercentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; at 25° C.; %): The stability toultraviolet light was evaluated by measuring a voltage holding ratioafter irradiation with ultraviolet light. A composition having a largeVHR-3 has a high stability to ultraviolet light. A TN device used formeasurement had a polyimide-alignment film and the cell gap was 5micrometers. A sample was poured into this device, and then the devicewas irradiated with light for 20 minutes. The light source was an ultrahigh-pressure mercury lamp USH-500D (produced by Ushio, Inc.), and thedistance between the device and the light source was 20 centimeters. Inthe measurement of VHR-3, a decreasing voltage was measured for 16.7milliseconds. The value of VHR-3 is preferably 90% or more, and morepreferably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A TN device intowhich a sample was poured was heated in a constant-temperature bath at80° C. for 500 hours, and then the stability to heat was evaluated bymeasuring the voltage holding ratio. A composition having a large VHR-4has a high stability to heat. In the measurement of VHR-4, a decreasingvoltage was measured for 16.7 milliseconds.

Response Time (τ; measured at 25° C.; millisecond): Measurement wascarried out with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. The low-passfilter was set at 5 kHz. A sample was poured into a VA device having anormally black mode, in which the cell gap between the two glasssubstrates was 4 micrometers, and the rubbing direction wasantiparallel, and then the device was sealed with a UV curable adhesive.Rectangular waves (60 Hz, 10 V, 0.5 second) were applied to the device.The device was simultaneously irradiated with light in the perpendiculardirection, and the amount of light passing through the device wasmeasured. The maximum amount of light corresponded to 100%transmittance, and the minimum amount of light corresponded to 0%transmittance. The response time was the period of time required for thechange from 90% to 10% transmittance (fall time; millisecond).

Specific Resistance (ρ; measured at 25° C.; Ωcm): A sample (1.0 mL) waspoured into a vessel equipped with electrodes. A DC voltage (10 V) wasapplied to the vessel, and the DC current was measured after 10 seconds.The specific resistance was calculated from the following equation:(specific resistance)=[(voltage)×(electric capacity of vessel)]/[(DCcurrent)×(dielectric constant in vacuum)].

Gas Chromatographic Analysis: A gas chromatograph Model GC-14B made byShimadzu Corporation was used for measurement. The carrier gas washelium (2 milliliters per minute). The sample injector and the detector(FID) were set to 280° C. and 300° C., respectively. A capillary columnDB-1 (length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer, dimethylpolysiloxane as the stationary phase, non-polar)made by Agilent Technologies, Inc. was used for the separation ofcomponent compounds. After the column had been kept at 200° C. for 2minutes, it was further heated to 280° C. at the rate of 5° C. perminute. A sample was dissolved in acetone (0.1% by weight), and 1microliter of the solution was injected into the sample injector. Arecorder used was a Model C-R5A Chromatopac Integrator made by ShimadzuCorporation or its equivalent. The resulting gas chromatogram showed theretention time of peaks and the peak areas corresponding to thecomponent compounds.

Solvents for diluting the sample may also be chloroform, hexane and soforth. The following capillary columns may also be used in order toseparate the component compounds: HP-1 made by Agilent Technologies Inc.(length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeter, film thickness 0.25 micrometer), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeter, filmthickness 0.25 micrometer). A capillary column CBP1-M50-025 (length 50meters, bore 0.25 millimeter, film thickness 0.25 micrometer) made byShimadzu Corporation may also be used for the purpose of avoiding anoverlap of peaks of the compounds.

The ratio of the liquid crystal compounds included in the compositionmay be calculated according to the following method. The liquid crystalcompounds are detected by use of a gas chromatograph. The ratio of peakareas in the gas chromatogram corresponds to the ratio (molar ratio) ofthe liquid crystal compounds. When the capillary columns described aboveare used, the correction coefficient of respective liquid crystalcompounds may be regarded as 1 (one). Accordingly, the ratio (percentageby weight) of the liquid crystal compounds can be calculated from theratio of peak areas.

The invention will be explained in detail by way of Examples. Theinvention is not limited by Examples described below. The compoundsdescribed in Comparative Examples and Examples were expressed as symbolsaccording to the definition in the following Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. A parenthesized number nextto the symbolized compound in Example corresponds to the number of adesirable compound. The symbol (−) means any other liquid crystalcompound. Ratios (percentage) of liquid crystal compounds mean thepercentages by weight (% by weight) based on the total weight of theliquid crystal composition. The liquid crystal composition furtherincludes an impurity. Last, characteristics of the composition aresummarized.

TABLE 3 Method of Description of Compounds using Symbols R—(A₁)—Z₁— . .. . . —Z_(n)—(A_(n))—R′ 1) Left-terminal Group R— Symbol C_(n)H_(2n+1)—n- C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn— CH₂═CH— V—C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn—C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn— CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn— 2) Right-terminal Group —R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn—C_(n)H_(2n)—CH═CH₂ —nV —CH═CF₂ —VFF —COOCH₃ —EMe 3) Bonding Group—Z_(n)— Symbol —C₂H₄— 2 —COO— E —CH═CH— V —C≡C— T —CF₂O— X —CH₂O— 1O—SiH₂— Si 4) Ring Structure —A_(n)— Symbol

H

Dh

dh

B

B(F)

B(2F)

B(2F,3F)

B(2F,3Cl)

B(2Cl,3F)

B(2F,5F)

Cro(7F,8F) 5) Example of Description Example 1. V2—BB(F)B-1

Example 2. 3-HB(2F,3F)—O2

Example 3. 3-HHB-1

Example 4. 5-HBB(F)B-3

Comparative Example 1

Example 21 was selected from the compositions disclosed in WO 2006-93189A. The basis of the selection was that this composition included thecompound (2-2-1), the compound (3-1-1), the compound (3-2-1) and thecompound (4-1-1). The components and characteristics of the compositionwere as follows. This composition was prepared, and measured accordingto the method described above, since there had been no mentioning of theresponse time.

3-HB—O1 (3-2-1)  8% 5-HB-3 (3-2-1)  8% 3-HH-4 (3-1-1)  7% 3-HH-5 (3-1-1) 7% 3-HB(2F,3F)—O2 (4-1-1) 14% 5-HB(2F,3F)—O2 (4-1-1) 14%2-HHB(2F,3Cl)-1 (2-2-1) 10% 3-HHB(2F,3Cl)-1 (2-2-1) 10% 3-HHB(2F,3Cl)—O2(2-2-1) 11% 5-HHB(2F,3Cl)—O2 (2-2-1) 11% NI = 63.9° C.; Tc ≦ −20° C.; Δn= 0.077; Δε = −3.1; τ = 10.1 ms.

Comparative Example 2

Example 15 was selected from the compositions disclosed in WO 2006-98289A. The basis of the selection was that this composition included thecompound (2-1-1), the compound (2-2-1), the compound (3-1-1), thecompound (3-2-1), the compound (3-5-1), the compound (4-1-1), thecompound (4-4-1) and the compound (4-7-1). The components andcharacteristics of the composition were as follows. This composition wasprepared, and measured according to the method described above, sincethere had been no mentioning of the response time.

3-HB(2F,3Cl)—O2 (2-1-1)   7% 3-HB(2Cl,3F)—O2 (2)  7% 3-HHB(2F,3Cl)—O2(2-2-1)  8% 3-HHB(2Cl,3F)—O2 (2)  8% 2-HH-5 (3-1-1)  5% 3-HH-4 (3-1-1)10% 3-HH-5 (3-1-1)  4% 3-HB—O2 (3-2-1)  8% 3-HB—O4 (3-2-1)  4% 3-HHB-1(3-5-1)  3% V-HHB-1 (3-5-1)  4% 3-HB(2F,3F)—O2 (4-1-1)  7%5-HB(2F,3F)—O2 (4-1-1)  7% 3-HHB(2F,3F)—O2 (4-4-1)  5% 5-HHB(2F,3F)—O2(4-4-1)  4% 3-HBB(2F,3F)—O2 (4-7-1)  5% 5-HBB(2F,3F)—O2 (4-7-1)  4% NI =81.1° C.; Tc ≦ −20° C.; Δn = 0.088; Δε = −2.8; τ = 10.6 ms.

Comparative Example 3

Example 7 was selected from the compositions disclosed in WO 2007-83561A. The basis of the selection was that this composition included thecompound (2-1-1), the compound (2-2-1), the compound (2-3-1), thecompound (3-1-1), the compound (3-2-1), the compound (3-5-1), thecompound (3-7-1) and the compound (4-7-1) . The components andcharacteristics of the composition were as follows. This composition wasprepared, and measured according to the method described above, sincethere had been no mentioning of the response time.

3-H2B(2F,3F)—O2 (4-2-1) 15% 3-HH2B(2F,3F)—O2 (4-5-1)  6% 3-HB(2F,3Cl)—O2(2-1-1) 15% 3-HHB(2F,3Cl)—O2 (2-2-1)  6% 3-HBB(2F,3Cl)—O2 (2-3-1)  9%3-HHB(2Cl,3F)—O2 (2)  6% 2-HH-5 (3-1-1)  4% 3-HH-4 (3-1-1) 10% 1V—HH-3(3-1-1)  7% 3-HB—O2 (3-2-1)  2% V—HHB-1 (3-5-1)  4% 2-BB(F)B-3 (3-7-1) 7% 3-HBB(2F,3F)—O2 (4-7-1)  9% NI = 79.6° C.; Tc ≦ −20° C.; Δn = 0.105;Δε = −2.9; τ = 11.1 ms.

Example 1

V—HB(2F,3F)—O2 (1-1-1) 15% V—HB(2F,3F)—O4 (1-1-1) 10% 2-HHB(2F,3Cl)—O2(2-2-1)  2% 3-HHB(2F,3Cl)—O2 (2-2-1)  3% 4-HHB(2F,3Cl)—O2 (2-2-1)  3%5-HHB(2F,3Cl)—O2 (2-2-1)  3% 2-HH-3 (3-1-1) 27% 3-HB—O2 (3-2-1)  2%3-HHB-1 (3-5-1)  6% 3-HHB-3 (3-5-1)  5% 3-HHB—O1 (3-5-1)  3%2-HBB(2F,3F)—O2 (4-7-1)  1% 3-HBB(2F,3F)—O2 (4-7-1) 10% 5-HBB(2F,3F)—O2(4-7-1) 10% NI = 74.7° C.; Tc ≦ −20° C.; Δn = 0.090; η = 19.6 mPa · s;Δε = −2.9; Vth = 2.16 V; τ = 6.5 ms; VHR-1 = 99.1%; VHR-2 = 98.1%; VHR-3= 98.1%.

Example 2

V—HB(2F,3F)—O2 (1-1-1) 14% V—H2B(2F,3F)—O2 (1-2-1) 10% V—HHB(2F,3F)—O2(1-4-1)  5% V2—HHB(2F,3F)—O2 (1-4-1)  5% V—HBB(2F,3F)—O2 (1-7-1) 10%V2—HBB(2F,3F)—O2 (1-7-1)  8% 2-HHB(2F,3Cl)—O2 (2-2-1)  2%3-HHB(2F,3Cl)—O2 (2-2-1)  3% V—HH-3 (3-1-1) 30% 1V—HH-3 (3-1-1)  4%V—HHB-1 (3-5-1)  6% V2—HHB-1 (3-5-1)  3% NI = 74.8° C.; Tc ≦ −20° C.; Δn= 0.091; η = 14.1 mPa · s; Δε = −2.9; Vth = 2.12 V; τ = 5.7 ms; VHR-1 =99.0%; VHR-2 = 98.0%; VHR-3 = 98.0%.

Example 3

V—H1OB(2F,3F)—O2 (1-3-1)  4% V2—H1OB(2F,3F)—O2 (1-3-1)  4%V—HH2B(2F,3F)—O2 (1-5-1)  5% V2—HH2B(2F,3F)—O2 (1-5-1)  5%3-HB(2F,3Cl)—O2 (2-1-1)  5% 3-HBB(2F,3Cl)—O2 (2-3-1)  2%5-HBB(2F,3Cl)—O2 (2-3-1)  3% V—HH-3 (3-1-1) 28% 3-HH-4 (3-1-1) 10%V2—BB-1 (3-3-1)  4% 5-HBB(F)B-2 (3-12-1)  4% 5-HBB(F)B-3 (3-12-1)  3%3-HB(2F,3F)—O2 (4-1-1)  5% 5-HB(2F,3F)—O2 (4-1-1)  5% 3-HH1OB(2F,3F)—O2(4-6-1)  5% 4-HH1OB(2F,3F)—O2 (4-6-1)  3% 5-HH1OB(2F,3F)—O2 (4-6-1)  5%NI = 74.6° C.; Tc ≦ −20° C.; Δn = 0.086; η = 15.2 mPa · s; Δε = −3.4; τ= 5.9 ms; VHR-1 = 99.0%; VHR-2 = 98.0%; VHR-3 = 98.0%.

Example 4

V—HB(2F,3F)—O2 (1-1-1) 10% V—HB(2F,3F)—O4 (1-1-1)  4% V—HHB(2F,3F)—O2(1-4-1)  4% V2—HB(2F,3F)—O2 (1-4-1)  4% V—HH1OB(2F,3F)—O2 (1-6-1)  3%V—HH1OB(2F,3F)—O4 (1-6-1)  4% 2-HHB(2F,3Cl)—O2 (2-2-1)  2%3-HHB(2F,3Cl)—O2 (2-2-1)  3% V—HH-3 (3-1-1) 32% V—HH-5 (3-1-1)  6%2-BB(F)B-3 (3-7-1)  5% 1-BB(F)B—2V (3-7-1)  5% 3-HBB(2F,3F)—O2 (4-7-1)10% 5-HBB(2F,3F)—O2 (4-7-1)  8% NI = 85.3° C.; Tc ≦ −20° C.; Δn = 0.108;η = 15.7 mPa · s; Δε = −2.9; Vth = 2.23 V; τ = 6.0 ms; VHR-1 = 99.0%;VHR-2 = 98.1%; VHR-3 = 98.0%.

Example 5

V—HB(2F,3F)—O2 (1-1-1) 10% V—HB(2F,3F)—O4 (1-1-1)  5% V—HBB(2F,3F)—O2(1-7-1)  6% V2—HBB(2F,3F)—O2 (1-7-1)  6% 2-HHB(2F,3Cl)—O2 (2-2-1)  2%3-HHB(2F,3Cl)—O2 (2-2-1)  3% 5-HHB(2F,3Cl)—O2 (2-2-1)  2% V—HH-3 (3-1-1)28% 7-HB-1 (3-2-1)  4% 1V—HBB-2 (3-6-1)  3% V2—BB(F) B-1 (3-7-1)  4%3-H2B(2F,3F)—O2 (4-2-1)  7% 5-H2B(2F,3F)—O2 (4-2-1)  7% 3-HHB(2F,3F)—O2(4-4-1) 10% 1O1—HBBH-5 (-)  3% NI = 73.6° C.; Tc ≦ −20° C.; Δn = 0.098;η = 17.7 mPa · s; Δε = −2.6; τ = 6.3 ms; VHR-1 = 99.2%; VHR-2 = 98.1%;VHR-3 = 98.0%.

Example 6

V—HB(2F,3F)—O2 (1-1-1) 10% V—HB(2F,3F)—O4 (1-1-1)  6% V—HHB(2F,3F)—O2(1-4-1)  5% V—HBB(2F,3F)—O2 (1-7-1)  5% V—HBB(2F,3F)—O4 (1-7-1)  5%2-HHB(2F,3Cl)—O2 (2-2-1)  2% 3-HHB(2F,3Cl)—O2 (2-2-1)  3% V—HH-3 (3-1-1)29% 3-HHEH-3 (3-4-1)  3% V—HHB-1 (3-5-1)  8% 5-HBBH-3 (3-10-1)  3%5-HB(F)BH-3 (3-11-1)  3% 3-H1OB(2F,3F)—O2 (4-3-1)  5% 5-H1OB(2F,3F)—O2(4-3-1)  5% 3-HH2B(2F,3F)—O2 (4-5-1)  8% NI = 84.3° C.; Tc ≦ −20° C.; Δn= 0.090; η = 19.2 mPa · s; Δε = −2.8; τ = 6.5 ms; VHR-1 = 99.1%; VHR-2 =98.1%; VHR-3 = 98.0%.

Example 7

V—HB(2F,3F)—O2 (1-1-1) 12% V—HB(2F,3F)—O4 (1-1-1) 10% 2-HHB(2F,3Cl)—O2(2-2-1)  2% 3-HHB(2F,3Cl)—O2 (2-2-1)  3% 3-HH—VFF (3-1)  5% 3-HH—O1(3-1-1)  5% V—HH-3 (3-1-1) 25% 5-HB—O2 (3-2-1)  3% 1V2—BB-1 (3-3-1)  3%3-HHB-1 (3-5-1)  4% 3-HB(F)HH-5 (3-8-1)  4% 2-HBB(2F,3F)—O2 (4-7-1)  4%3-HBB(2F,3F)—O2 (4-7-1) 10% 5-HBB(2F,3F)—O2 (4-7-1) 10% NI = 72.0° C.;Tc ≦ −20° C.; Δn = 0.095; η = 14.2 mPa · s; Δε = −2.6; τ = 5.7 ms; VHR-1= 99.0%; VHR-2 = 98.1%; VHR-3 = 98.2%.

Example 8

V—HB(2F,3F)—O2 (1-1-1) 14% V—HB(2F,3F)—O4 (1-1-1) 14% 3-HHB(2F,3Cl)—O2(2-2-1)  3% 4-HHB(2F,3Cl)—O2 (2-2-1)  2% 5-HHB(2F,3Cl)—O2 (2-2-1)  3%2-HH-3 (3-1-1) 13% 3-HH-4 (3-1-1) 10% 3-HB—O2 (3-2-1)  7% 3-HHB-1(3-5-1)  3% 3-HHB-3 (3-5-1)  2% 3-HHEBH-3 (3-9-1)  3% 3-HHEBH-4 (3-9-1) 3% 3-HHEBH-5 (3-9-1)  3% 3-HBB(2F,3F)—O2 (4-7-1) 10% 4-HBB(2F,3F)—O2(4-7-1) 10% NI = 81.3° C.; Tc ≦ −20° C.; Δn = 0.092; η = 20.3 mPa · s;Δε = −3.1; Vth = 2.18 V; τ = 5.7 ms; VHR-1 = 99.1%; VHR-2 = 98.2%; VHR-3= 98.2%.

The compositions of Examples 1 to 8 have a short response time incomparison with those in Comparative Examples 1 to 3. Thus, the liquidcrystal composition of the invention is so much superior incharacteristics to the liquid crystal compositions disclosed in thepatent documents No. 1 to No. 3.

Industrial Applicability

The invention provides a liquid crystal composition that satisfies atleast one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a large optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight and a high stability to heat, or that is suitably balanced betweenat least two of the characteristics. A liquid crystal display devicecontaining such a composition becomes an AM device that has a shortresponse time, a large voltage holding ratio, a large contrast ratio, along service life and so forth, and thus it can be used for a liquidcrystal projector, a liquid crystal television and so forth.

1. A liquid crystal composition having negative dielectric anisotropyand including at least one compound selected from the group of compoundsrepresented by formula (1) as a first component, at least one compoundselected from the group of compounds represented by formula (2) as asecond component, and at least one compound selected from the group ofcompounds represented by formula (3-4) and formulae (3-8) to (3-12) as athird component:

wherein R¹ is alkenyl having 2 to 12 carbons; R², R³, R⁴ and R⁵ areindependently alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; the ring Ais independently 1,4-cyclohexylene or 1,4-phenylene; Z¹ is independentlya single bond, ethylene, methyleneoxy or carbonyloxy; one of X¹ and X²is fluorine and the other is chlorine; and m and k are independently 1,2 or
 3. 2. The liquid crystal composition according to claim 1, whereinthe first component is at least one compound selected from the group ofcompounds represented by formula (1-1) to formula (1-7):

wherein R¹ is alkenyl having 2 to 12 carbons; and R² is alkyl having 1to 12 carbons, alkoxy having 1 to 12 carbons, alkenyl having 2 to 12carbons, or alkenyl having 2 to 12 carbons in which arbitrary hydrogenis replaced by fluorine.
 3. The liquid crystal composition according toclaim 1, wherein the second component is at least one compound selectedfrom the group of compounds represented by formula (2-1) to formula(2-3):

wherein R² and R³ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 4. The liquid crystal composition according to claim 1,wherein the ratio of the first component is in the range of 5% by weightto 70% by weight, the ratio of the second component is in the range of5% by weight to 30% by weight, and the ratio of the third component isin the range of 20% by weight to 70% by weight, based on the totalweight of the liquid crystal composition.
 5. The liquid crystalcomposition according to claim 1, further including at least onecompound selected from the group of compounds represented by formula (4)as a fourth component:

wherein R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; R⁶ is alkylhaving 1 to 12 carbons; the ring D is independently 1,4-cyclohexylene or1,4-phenylene; Z¹ is independently a single bond, ethylene, methyleneoxyor carbonyloxy; and p is 1, 2 or
 3. 6. The liquid crystal compositionaccording to claim 5, wherein the fourth component is at least onecompound selected from the group of compounds represented by formula(4-1) to formula (4-7):

wherein R² is alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine; and R⁶ isalkyl having 1 to 12 carbons.
 7. The liquid crystal compositionaccording to claim 5, wherein the ratio of the fourth component is inthe range of 5% by weight to 50% by weight based on the total weight ofthe liquid crystal composition.
 8. The liquid crystal compositionaccording to claim 1, wherein the maximum temperature of a nematic phaseis 70° C. or higher, the optical anisotropy (25° C.) at a wavelength of589 nanometers is 0.08 or more, and the dielectric anisotropy (25° C.)at a frequency of 1 kHz is −2 or less.
 9. A liquid crystal displaydevice containing the liquid crystal composition according to claim 1.10. The liquid crystal display device according to claim 9, wherein anoperating mode of the liquid crystal display device is a VA mode, an IPSmode or a PSA mode, and a driving mode of the liquid crystal displaydevice is an active matrix mode.